MATEC Web of Conferences 25 , 0 3 0 1 6 (2015)
DOI: 10.1051/ m atec conf/ 201 5 2 5 0 3 0 1 6
C Owned by the authors, published by EDP Sciences, 2015
One Low-cost Quartz Lamp Radiation Aerodynamic Heating Simulation
Experiment System with Control Law Flexible Adjustment Feature
Decheng Wang*
Automatic College, Northwest Polytechnical University, Xi’an, Shaanxi, China
Qiang Qin
China Aircraft Strength Institute, Xi’an, Shaanxi, China
Qikang Ren
Automatic College, Northwest Polytechnical University, Xi’an, Shaanxi, China
ABSTRACT: The quartz lamp radiation aerodynamic heating simulation experiment system plays an important
role on the structure strength heat experiment. In order to reduce its price and enhance flexibility on control law
design of experiment system, a design method for low-cost quartz lamp radiation aerodynamic heating simulation
experiment system with control law flexible adjustment feature is proposed. The hardware part is constructed by
taking Digital Signal Processor (DSP) as an implementing agency controller. The feedback temperature after
processed is computed by DSP. But the experiment process control value is computed by computer. The feedback temperature and experiment process control value data are transferred by serial communication model between DSP and computer. The experiment process relation data is saved by computer with EXCEL file, including the given target spectrum, the feedback temperature and the control value. The results of experiments on
system identification, PID spectrum tracking, different zone control and the open loop control show the effectiveness of the proposed method.
Keywords:
aerodynamic heating; quartz lamp radiation; temperature control; DSP
1 INTRODUCTION
Aerodynamic heating problem can bring many disadvantages to aircraft, such as structure stiffness reduction, intensity weaken, thermal stress, thermal strain
and material ablation, especially for hypersonic flight
condition. It must be considered in the design of aircraft structure strength [1-3]. There are some kinds of
methods for simulating aerodynamic heating, such as
convective heating, radiation heating and conduction
heating [4-6]. As the radiation heating source, quartz
lamp has following advantages such as the easier operation, lower expense, easier control for different
zones, and the copy shape heater designed with test
specimen. These advantages make quartz lamp become the most commonly-used heating source in aerodynamic heating simulation experiment instead of
other heating ways.
Some design methods for quartz lamp radiation
aerodynamic heating simulation experiment system
have been proposed. Those methods can be divided
into two kinds. The first kind of method is based on
Programmable Logic Controller (PLC) [7, 8]. The
close-loop control function and the feedback data
acquisition are carried out by PLC and the price of
PLC is very expensive. In the actual experiment process, the controller is far away from test specimen.
The thermocouple output signal is overlaid disturb-
ance noise due to long distance transmission and space
disturbance produced power switching device. The
overlaid disturbance noise can reduce feedback signal
measurement accuracy. Thus it can affect the control
performance and the data communication speed can
limit the control period. The second kind of method is
based on I/O card and computer [9, 10]. The control
function is carried out by computer. The feedback data
acquisition is carried out by I/O card. The data communication speed problem is avoided, but the small
signal transfer disturbance noise problem still exists.
This kind of experiment system is also expensive due
to high price of I/O card. The feedback temperature
channel number is limited, because the input channel
of I/O card is few. The design of low-cost quartz lamp
radiation aerodynamic heating simulation experiment
has good demand. Because the quartz lamp radiation
aerodynamic heating simulation experiment system
has great nonlinear features, it is difficult to get the
good spectrum tracking result. Much time is used to
debug spectrum tracking. The data storage ability is
very important for good spectrum tracking.
Aiming to the low-cost quartz lamp radiation aerodynamic heating simulation experiment system design
and enhance the data storage ability, this paper proposed an experiment system design method based on
DSP and computer. The experiment result shows that
the proposed control method has good performance,
*Corresponding author: wangdecheng@nwpu.edu.cn
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Article available at http://www.matec-conferences.org or http://dx.doi.org/10.1051/matecconf/20152503016
MATEC Web of Conferences
Power convert
device
AC voltage
Heater
Test
specimen
Temperature
Controller
Computer
Signal convert
Figure 1. Hardware structure schematic diagram
improving the effectiveness of the aerodynamic heating simulation experiment.
2 HARDWARE
SYSTEM
DESIGN
OF
EXPERIMENT
The hardware structure of the proposed quartz lamp
radiation aerodynamic heating simulation experiment
system is shown in Figure 1.
The AC voltage part provides the original energy to
experiment system. It directly adopts three-phase AC
380V provided by power supply system.
The function of the power convert device part is to
dynamically adjust the quartz lamp input voltage,
providing the basis for heat condition close-loop control. It is constructed by single phase AC regulating
voltage module. The model number is LTVDH-380V
-120A. This module is controlled by analog voltage
signal with range scope from 0V to 5V. This analog
voltage signal has a certain relationship between the
input voltage and the output voltage of quartz lamp.
As the input control voltage changing, the quartz lamp
input voltage is changed. There is electrical isolation
feature between the control signal and the high voltage
signal, enhancing the system safety performance.
The heater is constructed by a series of quartz lamps.
The input voltage of each quartz lamp can be 380V. In
order to improve the heat flux output ability, reflectance coating on the surface of quartz lamp is adopted.
The test specimen depends on the experiment object.
Different experiments may have different test specimens. Its temperature change is controlled by quartz
lamp radiation heat transfer, and its temperature is
measured by thermocouple. In our following experiment, the material of the test specimen is titanium
alloy with TB type. The K-type thermocouple is used.
The signal convert part is used to convert small
voltage signal of thermocouple into big voltage meeting the requirement of following-up part. This part can
be placed near the test specimen. The noise produced
by long distance transmission and power switching
device space disturbance can be solved effectively. By
amplified this small signal, the controller can carry out
more accurate acquisition of feedback signal. The
model number of signal convert part is DS-22-111AD.
Its working power source is 24V.
The function of the controller part is different from
traditional controller with auto-computing feature of
control value. Its function has three parts: the feedback
temperature acquisition, the control vale output and
the data communication. It is constructed by DSP with
TMS320F2812. In order to achieve corresponding
function, the DSP minimum system is constructed. It
includes following parts such as power supply part,
JTAG part, crystal oscillator part and digital level
changing part. The power supply part mainly provides
3.3V and 1.9V by 5V input power supply with special
power supply chip. The JTAG part is used to debug
the program by online model. After finished the program debugging, the program is programmed in flash
memory. The frequency of crystal oscillator is 30MHz.
Digital level changing part mainly achieves the digital
voltage change which is between 5V and 3.3V. In
order to get feedback of temperature, it will acquire
the voltage signal using inner analog to digital converter’s peripheral function. Sixteen channels’ signals
can be connected to DSP at the same time. The controller and the computer build the communication
relationship by serial communication. The controller
sends temperature information to computer. It also
receives control value by this digital communication
model. In order to achieve digital level changing, the
specific communication application chip max3232 is
used. What’s more, it outputs analog voltage to
change output of the power convert device. Because
TMS320F2812 inner does not have digital to analog
converter function in peripheral, the implement of
digital to analog converter function depends on circuit
design. Taken into consideration of concise circuit
design, the serial digital to analog converter module is
adopted. The corresponding analog converter device
module number is TLC 5615.
The function of computer includes following parts,
such as control vale computing, human-computer
interaction, data communication and data storage. By
serial communication, the computer can get feedback
temperature and send control vale to DSP. The implement of human-computer interaction function depends on the software design. By human-computer
interaction, the operator can design the experiment
target spectrum. The experiment process condition can
be monitored and the control law parameters can be
set freely. By control law and feedback temperature
information, it produces new control value. The experiment process data is saved in EXCEL file, including the target spectrum data, the feedback temperature
data and the control value data.
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The whole experiment system hardware is shown in
Figure 2 and Figure 3. Figure 2 mainly contains the
controller part and the signal convert part. The
switching power supply is used to provide working
power supply with 5V and 24V. Figure 3 mainly contains the heater part, the power convert device part and
the test specimen part. The breaker is used to improve
the system safety performance.
The buffer register data is sent to computer by serial
model under the baud rate control. In analog signal
output part, the serial clock signal and the enable signal are provided by digital output signal with input/output function of peripheral. In sampling part, the
timer is used to realize equal internal sampling. The
filtering part is used to reduce the noise influence on
feedback temperature accuracy measurement.
Begin
Program initialization
Communication protocol initialization
Load correlation experiment data
Read feedback temperature data
Figure 2. The controller part and the signal convert part
Generate control value by control law
Send control value
Experiment process end?
N
Y
Saved experiment data
End
Figure 3. The heater part, the power converter device part
and the test specimen part
3 SOFTWARE DESIGN OF EXPERIMENT SYSTEM
The software design is divided into two parts, including the controller software part and the computer
software part.
The controller software part is carried out by
TMS320F2812. It is developed by Code Composer
Studio (CCS) with C language. The corresponding
program function can be divided into five parts: data
acceptance, data transmission, analog signal output,
sampling and filtering. The data acceptance part is
implemented by interrupting way. When the acceptance interrupt happened, the data saved in the
corresponding receiving data buffer register is assigned to the variable. The data transmission part is
implemented by inquiring way. By equal time interval,
the data will be written into the corresponding transmission data buffer register, as buffer register empty.
Figure 4. Computer software flow chart
The computer software part is carried out by computer. It is developed by LabWindows/CVI based on
C language. It mainly provides the human-computer
interaction interface. The corresponding program
function can be divided into five parts: data acceptance, data transmission, data saving, control value
computing. The corresponding program flow chart is
shown in Figure 4. The experiment correlation data is
saved in EXCEL file. Before the beginning of experiment, the target spectrum should be given by EXCEL
file style. The aim of communication protocol initialization is to ensure the serial communication reliability.
By reading corresponding EXCEL file, the target
spectrum data is assigned to the corresponding array.
In order to keep the same control period, the timer is
adopted. At the beginning of the experiment, the timer
is enabled. At the end of the experiment, the timer is
shut off. By comparing the feedback temperature and
the target spectrum, the new control value is produced
based on the corresponding control law. The target
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4 EXPERIMENTAL ANALYSIS
In order to verify effectiveness of the proposed quartz
lamp radiation aerodynamic heating simulation experiment system, the flowing experiment is carried
out.
It is very important for experiment system with
system identification feature. The reason is summarized as the following two aspects. The first one is that
the system identification can give the guidance for
control law design by traditional parameter adjustment
method. The second one is that the system identification provides a basis for experiment system feature
analysis. And the first experiment is carried out on
system identification. The control signal of power
convert device is selected as the system identification
of given signal. The given signal is changed with
range which is from 1V to 3V by interval with 0.5V,
and each stage lasts 3 minutes. The feedback temperature is shown in Figure 5. This feedback curve can be
used to construct an implementing agency model by
mechanism analysis. It can be also used to conduct the
control law design.
sult conducting parameters design. The given spectrum curve and the feedback temperature curve are
plotted in Figure 6. We cannot recognize these two
curves, because the tracking result is very good.
Different positions on weapon may have different
thermal characteristics because of flight characteristics.
Thus, different places on test specimen may have different target spectrum during experiment process.
Different zone control ability is very important for
aerodynamic heating simulation experiment system
and the third experiment is carried out on different
zone control. Figure 7 gives different zone control
results. Two different zones are given different target
spectrum. The design of controller parameters is also
based on the system identification result. The given
target spectrum and the feedback temperature curve
are plotted in the same figure. We cannot recognize
these two curves, because the tracking result is very
good.
500
400
Temperature(ć )
spectrum data, feedback temperature data and control
value data are saved in different array. Whether the
experiment process finished depends on checking the
target spectrum data. After the experiment process
finished, those experiment process data are saved by
writing EXCEL file. At the end of experiment process,
the control value is set to zero in order to enhance the
experiment safety performance.
200
100
500
0
400
0
3
6
9
Time(min)
12
15
Figure 6. PID spectrum tracking result
300
500
200
400
100
0
0
3
6
9
Time(min)
12
15
Temperature(ć )
Temperature(ć )
300
300
200
100
Figure 5. Feedback temperature for system identification
The most commonly-used spectrum tracking debug
method is PID. The second experiment is carried out
on PID tracking. By the proposed experiment system,
PID parameters, including the proportional parameter,
the integral parameter and the differential parameter,
can be set freely. Figure 6 gives a PID spectrum
tracking result based on the system identification re-
0
0
3
6
9
Time(min)
12
15
Figure 7. Different zone control results
The given target spectrum used in aerodynamic
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heating simulation experiment has stable feature during the whole experiment process. This feature gives
the operator the chance using some new control
methods and debugging spectrum tracking, such as
repetitive learning method and iterative learning
method. When those methods are used, the experiment
system should have the control value storage function,
because those control values are used to design new
control value. The fourth experiment is carried out in
order to show the control value storage function of
experiment system. The open loop control with control value used in second experiment is shown in Figure 8. It has similar feedback result with Figure 6.
500
Temperature(ć )
400
300
200
100
0
0
3
6
9
Time(min)
12
15
Figure 8. Open loop control result
5 CONCLUSION
Aiming at quartz lamp radiation aerodynamic heating
simulation experiment design problem, this paper
gives an experiment system design method. Compared
with traditional method, it is low-cost because of taking DSP as controller. The software design makes the
experiment system has following functions, such as
system identification, PID tracking, different zone
control and control value storage. The experimental
analysis result shows the effectiveness of the proposed
method based on corresponding experiment analysis.
It can provide an effective way for aerodynamic heating simulation experiment.
ACKNOWLEDGEMENT
The authors would like to acknowledge support from
Aeronautical Science Foundation of China (Grant No.
20140953016). And the authors would also like to
thank all the reviewers for their precious comments.
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